Please help!

We have been together for 9 years and been married for 7 months. We both want a baby so bad but i dont feel like we are trying hard enough. My husband doesnt like sex even if i try to start something he will have an excuse. Maybe once a month seems like its enough for him. When people asks us about having a baby he will say we are trying but nothing happens we must see a dr. But i think why we arent getting pregnant is because of no sex. What can i do or what do you think might be his problem?